Yes.
Interesting observation. I suppose another point to consider is whether the diverted XC service is slowed down by the local stopper on that line?
You'd have to be unlucky!
Do your examples have to be possible by a direct through train? You may want to edit your opening post to make this clear. If not, the examples are almost infinite!
A few more examples which
are possible by through trains:
Glasgow to Edinburgh - via Falkirk faster than via Shotts or via Bathgate
London to Birmingham - Euston to New St via Rugby faster than Marylebone to Moor St via High Wycombe
London to Horsham - faster via Gatwick on GTR but SWR is more direct
Wakefield to Sheffield - faster via Moorthorpe but via Barnsley is more direct
London to Exeter - faster from Paddington but the distance is longer than from Waterloo via Salisbury
Wigan to Manchester - fast trains go via Eccles but the Hag Fold route is shorter
Sunderland to York - LNER's daily through train is faster than Grand Central despite taking a longer route via Newcastle